1967 Johnson 20hp Short to Long shaft conversion

I have a 1967 Johnson (FD-21) 20hp short shaft. Motor is perfect. Runs great and is very reliable. Not to mention it has been in my family since before I was born. So I am kind of attached to the motor. I came across a 15ft boat and trailer for dirt cheap. The boat has a 20" transom. I placed the motor on the boat and the cavation plate is about 2" above the bottom of the transom.

First question?...... Is the cavation plate 2" above the transom too far and will this affect the performance of the motor?

2nd question?....... I found a conversion kit (all part included and pretty cheap) to place the 5" spacer to convert it to a long shaft. However, someone to me that putting 5" spacer in it is not a good idea? Any thoughts? Also, how hard of a conversion is this? Would I be better of finding a long shaft lower unit?

Thanks for any help.

Re: 1967 Johnson 20hp Short to Long shaft conversion

All long shaft versions of that motor were by means of conversion kits, whether installed at the factory or afterwards. So, the "somebody" is mistaken.

It's not a hard job. Same as a water pump repair.

Re: 1967 Johnson 20hp Short to Long shaft conversion

here's and idea, just mount it so that the AV plate is about 1" above the bottom. i think i would try the present set up first. #1 concern is, is it getting enough water to cool. you're short now and going to be long afterward. so you may still need the plate.
http://www.iboats.com/Mini_Jacker/d...d.217144--list_time.1176324254--view_id.40133

Re: 1967 Johnson 20hp Short to Long shaft conversion

Thanks for the help. I had already looked into the mini-jack plate and was considering it and curious to how well it would work. Now that someone else seems to have the same idea I might go ahead and try that. Seems to be the cheapest and less labor intensive option. I will report in with results later.